This control-flow construct, introduced in Elixir 1.2, accepts one or more expressions, a do block, and optionally an else block. It allows you to use pattern matching on the return value of each expression, running the do block if every pattern matches. If one of the patterns doesn't match, two things may happen: If provided, the else block will be executed; otherwise, it will return the value that didn't match the expression. In practice, with allows you to replace a chain of nested instances of case or a group of multi-clause functions.
To demonstrate the usefulness of with, let's see an example:
iex> options = [x: [y: [z: "the value we're after!"]]] [x: [y: [z: "the value we're after!"]]]iex> case Keyword.fetch(options, :x) do
